The HCCI engine offers tantalizing potential for low hydrocarbon emissions and low NOx emissions coupled with significant fuel economy improvement. Unlike its better known compression ignition cousin, the diesel engine, the HCCI engine may be operated soot free and also with low NOx emissions because there is no locally rich zone of combustion. Rather, ignition occurs spontaneously and concurrently at many points in the combustion chamber. A problem heretofore, however, has resided in the lack of capability to precisely control the onset of the ignition event. The present invention solves this problem.
Another problem with previous HCCI engines was the apparent inability to operate satisfactorily on fuels having a wide range of cetane or octane ratings. An engine according to this present invention has adaptable timing capability which will allow fuel quality to be accurately and adequately handled.